Kaplan Raphael, Bush Daniel, Bisby James A, Horner Aidan J, Meyer Sofie S, Burgess Neil
University College London.
Universitat Pompeu Fabra, Barcelona, Spain.
J Cogn Neurosci. 2017 Mar;29(3):507-519. doi: 10.1162/jocn_a_01064. Epub 2016 Oct 25.
Hippocampal-medial prefrontal interactions are thought to play a crucial role in mental simulation. Notably, the frontal midline/medial pFC (mPFC) theta rhythm in humans has been linked to introspective thought and working memory. In parallel, theta rhythms have been proposed to coordinate processing in the medial temporal cortex, retrosplenial cortex (RSc), and parietal cortex during the movement of viewpoint in imagery, extending their association with physical movement in rodent models. Here, we used noninvasive whole-head MEG to investigate theta oscillatory power and phase-locking during the 18-sec postencoding delay period of a spatial working memory task, in which participants imagined previously learned object sequences either on a blank background (object maintenance), from a first-person viewpoint in a scene (static imagery), or moving along a path past the objects (dynamic imagery). We found increases in 4- to 7-Hz theta power in mPFC when comparing the delay period with a preencoding baseline. We then examined whether the mPFC theta rhythm was phase-coupled with ongoing theta oscillations elsewhere in the brain. The same mPFC region showed significantly higher theta phase coupling with the posterior medial temporal lobe/RSc for dynamic imagery versus either object maintenance or static imagery. mPFC theta phase coupling was not observed with any other brain region. These results implicate oscillatory coupling between mPFC and medial temporal lobe/RSc theta rhythms in the dynamic mental exploration of imagined scenes.
海马体与内侧前额叶的相互作用被认为在心理模拟中起着关键作用。值得注意的是，人类额叶中线/内侧前额叶皮质（mPFC）的θ节律与内省思维和工作记忆有关。与此同时，有人提出，在图像中视点移动期间，θ节律可协调内侧颞叶皮质、压后皮质（RSc）和顶叶皮质的处理过程，这扩展了它们在啮齿动物模型中与身体运动的关联。在这里，我们使用非侵入性全脑MEG来研究空间工作记忆任务的18秒编码后延迟期内的θ振荡功率和锁相，在该任务中，参与者在空白背景上想象先前学习的物体序列（物体维持），从场景中的第一人称视角想象（静态图像），或沿着经过物体的路径移动想象（动态图像）。与编码前基线相比，我们发现mPFC中4至7赫兹的θ功率增加。然后，我们检查了mPFC的θ节律是否与大脑其他部位正在进行的θ振荡相位耦合。对于动态图像，同一mPFC区域与后内侧颞叶/RSc的θ相位耦合显著高于物体维持或静态图像。未观察到mPFC与任何其他脑区的θ相位耦合。这些结果表明，在对想象场景的动态心理探索中，mPFC与内侧颞叶/RSc的θ节律之间存在振荡耦合。
